A text search configuration specifies all options necessary to
transform a document into a tsvector: the
parser to use to break text into tokens, and the dictionaries to
use to transform each token into a lexeme. Every call of
to_tsvector or to_tsquery needs a text search configuration to
perform its processing. The configuration parameter default_text_search_config
specifies the name of the default configuration, which is the one
used by text search functions if an explicit configuration
parameter is omitted. It can be set in postgresql.conf, or set for an individual session
using the SET command.

Several predefined text search configurations are available, and
you can create custom configurations easily. To facilitate
management of text search objects, a set of SQL commands is available, and there are
several psql commands that display
information about text search objects (Section 12.10).

As an example we will create a configuration pg, starting by duplicating the built-in english configuration:

SELECT * FROM ts_debug('public.pg', '
PostgreSQL, the highly scalable, SQL compliant, open source object-relational
database management system, is now undergoing beta testing of the next
version of our software.
');

The next step is to set the session to use the new
configuration, which was created in the public schema: